1. Field of the Invention
The present invention relates to devices for the stacking a random sized documents delivered at high speeds in a spaced apart relationship. Upon completion of the stacking operation, two adjacent edges of the randomly sized documents are stacked in register.
2. Description of the Prior Art
Stacking devices of the rotating delivery fan or spiral carrier type are well known. Such devices use a rotating member, such as, a drum or a plurality of discs mounted for rotation on a common axis. The rotating member contains a plurality of arcuateshaped, evenly spaced receiving slots designed to receive an item fed at a relatively high rate and to substantially decelerate the item. Sections or walls of the rotating member, which are shaped to a thin edge to present a minimum edge profile, separate adjacent slots. An item is fed by any suitable delivery or feeding mechanism, such as a system of feed belts and rollers, into one of the receiving slots. When the rotating member is formed from a plurality of discs, a deflector may extend from the feed mechanism into the space between adjacent discs to ensure proper insertion of an item into a slot. It is also known to at least partially enclose the rotating member with a fixed arcuate-shaped member to aid in the retention of items within the rotating member. After an item has been inserted into a slot, the rotating member advances the item to a stripping station where a stripping member, positioned in the space between adjacent discs, engages the leading edge of the item, removes the item from the rotating member, and transfers the item to a conveyor belt or stacking table. Descriptions of stacking devices of the previously described type are found in U.S. Pat. No. 1,956,541, entitled "Delivery Mechanism for Printing Machines"; U.S. Pat. No. 3,162,439, entitled "Document Stacking Devices"; and U.S. Pat. No. 3,847,384, entitled "Apparatus for Collating Sheet-Like Elements".
It is known, in stacking devices of the aforementioned type, to use deflecting means between the delivery mechanism and the rotating member. For instance, U.S. Pat. No. 2,403,062, entitled "Delivery Mechanism for Printing Machines", teaches the use of a solenoid-actuated lever or "kicker" rotatably mounted adjacent the rotating member. The lever is actuated to prevent spoiled copies from reaching the rotating member. In U.S. Pat. No. 3,313,538, entitled "Automatic Guide-Out for Printed Papers from a Rolling Press," arcuate-shaped guide-out boards are provided between the delivery mechanism and the rotating member to divert a document or sheet to an inspection station. In U.S. Pat. No. 3,851,872, entitled "Sorting Apparatus for Collating Simplex and Duplex Copies", a deflector gate member is provided to deflect copy sheets down one of two paths leading to a rotating member. Copy sheets following the first path will be inserted into the rotating member face-up. Copy sheets following the second path will be inserted into a different area of the rotating member face-down.
When stacking devices of the aforementioned type are used, the leading edge of each item must be in phase with the rotation of the rotating member so that successive items will properly enter the receiving slots in the member. Maintaining this necessary synchronization between the speed of rotation of the rotating member and the rate of delivery of items can become extremely difficult. This is particularly true when either different batch sizes or intermixed size items are handled. Synchronization becomes even more difficult when the feeding of items is random and/or intermittent. One solution to the problem of synchronization is described in U.S. Pat. No. 3,531,108, entitled "Document Stacker and/or Sorter", which discloses the use of a stacking device having a sensor for sensing the position of the slots in the rotating member and a sensor for sensing the position of the item in the delivery mechanism. Depending upon the relationship between the position of the item and the receiving slot, the item is either accelerated or decelerated over a short distance within the document handling system to bring it into phase or synchronization with the slot in the rotating member. Another solution to the synchronization problem involves the use of a deflector member to direct a document to alternate paths having different discrete lengths. These known solutions require the use of complex, expensive equipment to precisely control the rate of rotation of the rotating member, the rate of delivery of items to the rotating member, and/or the spacing between items fed to the rotating member.